A Geomedical Survey: Is There an Association Between Climatic Conditions and Leishmania Species Distribution in Iran During the Years 1999–2021?

Acta Parasitologica (2024) 69:769–775 https://doi.org/10.1007/s11686-024-00811-4 ORIGINAL PAPER A Geomedical Survey: Is There an Association Between Climatic Conditions and Leishmania Species Distribution in Iran During the Years 1999–2021? Zahra Navi1 · Abdolreza Salahi‑Moghaddam2 Homa Hajjaran1 · Màrius V. Fuentes4 · Majid Habibi‑Nokhandan3 · Mehdi Mohebali1 · Received: 30 June 2023 / Accepted: 19 January 2024 / Published online: 28 February 2024 © The Author(s) 2024 Abstract Purpose Iran is among the high-risk leishmaniasis regions in the world. WHO recommends the use of GIS as an ideal tool for healthcare authorities to predict the evolution of a disease, delimit the risk of outbreaks and identify critical areas. The aim of this research is to find the association between the main species of Leishmania (L. major, L. tropica, L. infantum) dispersion and climatic variables in Iran. Methods All molecular-based reports of leishmaniasis from Iran between 1999 and 2021 were gathered from reliable medical sources. Meteorological data (air and soil temperatures, annual rainfall and humidity) of the country along the study period were obtained from the Iranian Climatological Research Centre. The data concerning species distribution and climatic conditions during this period were moved to a base-map through raster layers using ArcGIS 10.4.1 software. The relationship between parasitological and climatic models was examined using ANOVA. Results High risk area maps, based on the cut-off thresholds, were generated for Leishmania major, L. tropica and L. infantum. According to the molecular-based reports, the L. major distribution was significantly related to all climatic variables, while L. tropica was merely related to rainfall and humidity, and the L. infantum distribution was significantly associated with rainfall, soil and air temperatures. Conclusion The association between climatic conditions and Leishmania species distribution in Iran has been confirmed. Consequently, both, the relationship between climatic conditions and the geographical distribution of Leishmania species, and the use of GIS to better understand the spatial epidemiology of leishmaniasis, have been reaffirmed. Keywords Leishmania · Climatic data · Epidemiology · GIS · Predicting map · Iran Introduction * Homa Hajjaran * Màrius V. Fuentes 1 Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Poor Sina Avenue Qods ST, Keshavarz Blvd, 1417613151 Tehran, Iran 2 Eco-Parasitologist, Aban Monife Institute of Public Health Research, Tehran, Iran 3 Climatological Research Institute, Mashhad, Iran 4 Parasites and Health Research Group, Departament de Farmàcia iI Tecnologia Farmacèutica i Parasitologia, Facultat de Farmàcia, Universitat de València, Av. Vicent Andrés Estellés s/n, Burjassot, 46100 València, Spain Leishmaniasis, a vector-borne parasitic disease, presents clinical manifestations which range from self-healing primary skin infections, in the case of cutaneous leishmaniasis, to incurable Kala-Azar, in the case of visceral leishmaniasis [1]. Leishmania parasites are mainly transmitted through zoonotic or anthroponotic routes, i.e. by bites of phlebotomine sandfly species [2]. Difficulties in leishmaniasis elimination and its control are rooted in poor vector (sandfly) management, the fact that there is no vaccine available, and the lack of new effective treatments [3]. The wide diversity of Leishmania species in 98 countries around the world has been documented. The scientific literature shows that about 350 million people worldwide are at risk of leishmaniasis, and an annual incidence of 700,000 Vol.:(0123456789) 770 to 1 million has been reported [4–7]. Although the actual number of human cases of cutaneous and visceral leishmaniasis is unknown, both have been expanding during the last decades [8–10]. Leishmaniasis shows a rising prevalence with a high incidence, especially in Mediterranean countries and across Europe [11]. As an example, the population of Barcelona (Spain) experienced a growing trend of leishmaniasis from 1996 to 2019, which was statistically significant between 2016 and 2019 [12]. Some researchers suggest that this obvious increase of vector borne diseases, such as leishmaniasis, might be due to climate change [13, 14]. Human health is affected by various environmental factors, especially in places of residence, so that it should be considered that most health issues have a spatial dimension [15]. In addition, some research has shown the influence of climate change on vector populations and, consequently, on the incidence of vector borne diseases, such as malaria, chikungunya, dengue, yellow fever, and zika [16, 17]. Geographic Information Systems (GIS) consist of hardware, software, geographic data, human resources, as well as other layers that display the results in the form of maps which can be analyzed for ecological and epidemiological aims [18]. Preparing a map of the occurrence of the disease at a particular point or region based on GIS, does not only protect communities of risk factors, but also influences the strategy of healthcare management [19]. Delimiting the risk of outbreaks and identifying critical areas by epidemiologists can open up new lines for healthcare authorities to create plans to prevent the spread of a disease [20]. WHO has recommended the use of GIS as an ideal tool to predict the future evolution of a disease in various areas and to analyse the relation between geographic health problems in communities and their natural environment [19]. The aims of this research are the following: – to study the climatic conditions in the areas that are the centres of visceral and cutaneous leishmaniasis in Iran during the years 1999-2021; – to identify climatic factors that increase the risk of an area turning into a hotspot region of cutaneous and visceral leishmaniasis; and to establish the association between the main species of Leishmania (L. major, L. tropica, L. infantum) dispersion and climatic variables. Materials and Methods Study Site This study was conducted at a national scale in Iran, located in west Asia, covering a land mass of 1,648,195 k m2, bordering the Caspian Sea in the north as well as the Persian Gulf and the Oman Sea in the south, and having borders with Acta Parasitologica (2024) 69:769–775 Afghanistan, Armenia, Azerbaijan, Iraq, Pakistan, Turkey and Turkmenistan [21]. Data Collection Parasitological data consisted of all molecular-based reports of leishmaniasis in Iran from 1999 to 2021, which were gathered from reliable medical sources. For the purpose of the current study, articles that report the number, type and geographical distribution of human leishmaniasis cases in Iran through molecular tests from 1999 to 2019 were collected based on a literature review previously published by our colleagues in 2021 [22]. We followed their method and added 11 new artic (...truncated)